摘要
碳酸盐岩裂缝性地层在钻进过程中常出现由气液重力置换导致的溢漏同存现象,造成井下复杂、井控困难和储层伤害。笔者建立了气液重力置换室内实验装置,可模拟溢漏同存工况,具有裂缝尺寸、钻井液性能等关键参数可调、数据自动采集与分析、置换过程可视化等特点。基于该装置模拟了气液重力置换现象,可观察到裂缝中存在明显的气液分界面。通过改变裂缝宽度、裂缝钻开程度、钻井液黏度、井底压力等参数,研究了裂缝性地产气液重力置换特点。研究结果表明:漏失速率随裂缝缝宽和裂缝钻开程度的增加而增加,且对裂缝宽度更为敏感,而钻井液黏度增大对气液重力置换的抑制效果明显。基于室内实验结果,提出了气液重力置换的预防措施,可为碳酸盐岩裂缝性地层安全钻井施工提供参考。
During the drilling process of fractured carbonate formations,the coexistence of well kick and loss caused by the displacement of gas and liquid gravity often leads to downhole complexity,difficulty in well control and reservoir damage.In this study,an indoor experimental device for gas and liquid gravity displacement is created to simulate the coexisting well kick and mud loss,characterized by the adjustable key parameters such as fracture size and drilling fluid performance,automatic data acquisition and analysis,displacement process visualization and so on.The phenomenon of gas-liquid gravity displacement is simulated using this new device,by which an obvious gas-liquid interface can be observed in fractures.By changing the fracture width,fracture opening degree,drilling fluid viscosity,bottom hole pressure and other parameters,this paper analyzes the characteristics of gas-liquid gravity displacement in fractured formation.The results show that the loss rate increases with the fracture width and opening degree rising,more sensitive to fracture width.In the meantime,the increase of drilling fluid viscosity has an obvious suppression effect on gas-liquid gravity displacement.Based on the results of laboratory experiments,the preventive measures for gas-liquid gravity displacement are proposed,which can provide references for safe drilling in carbonate fractured formations.
出处
《石油学报》
EI
CAS
CSCD
北大核心
2018年第10期1186-1192,共7页
Acta Petrolei Sinica
基金
国家自然科学基金重点项目(No.51734010、No.51334003)
中国石油天然气集团公司科技重大专项(2016E-0608)资助
关键词
裂缝
气液重力置换
可视化实验
影响因素
预防措施
fracture
gas-liquid gravity displacement
visual experiment
influence factor
preventive measure
